using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using SatelliteProvider.Common.Configs;
using SatelliteProvider.Common.Interfaces;

namespace SatelliteProvider.Services;

public class RegionProcessingService : BackgroundService
{
    private readonly IRegionRequestQueue _queue;
    private readonly IRegionService _regionService;
    private readonly ProcessingConfig _processingConfig;
    private readonly ILogger<RegionProcessingService> _logger;

    public RegionProcessingService(
        IRegionRequestQueue queue,
        IRegionService regionService,
        IOptions<ProcessingConfig> processingConfig,
        ILogger<RegionProcessingService> logger)
    {
        _queue = queue;
        _regionService = regionService;
        _processingConfig = processingConfig.Value;
        _logger = logger;
    }

    protected override async Task ExecuteAsync(CancellationToken stoppingToken)
    {
        _logger.LogInformation("Region Processing Service started with {MaxConcurrent} parallel workers", 
            _processingConfig.MaxConcurrentRegions);

        var workers = new List<Task>();
        for (int i = 0; i < _processingConfig.MaxConcurrentRegions; i++)
        {
            var workerId = i + 1;
            workers.Add(ProcessRegionWorkerAsync(workerId, stoppingToken));
        }

        await Task.WhenAll(workers);

        _logger.LogInformation("Region Processing Service stopped");
    }

    private async Task ProcessRegionWorkerAsync(int workerId, CancellationToken stoppingToken)
    {
        if (workerId > 1)
        {
            var startupDelay = Random.Shared.Next(100, 500);
            await Task.Delay(startupDelay, stoppingToken);
        }

        while (!stoppingToken.IsCancellationRequested)
        {
            try
            {
                var request = await _queue.DequeueAsync(stoppingToken);
                
                if (request != null)
                {
                    await _regionService.ProcessRegionAsync(request.Id, stoppingToken);
                }
            }
            catch (OperationCanceledException)
            {
                break;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Worker {WorkerId}: Error processing region request", workerId);
            }
        }
    }
}